Objectives: Availability of atrial electrograms (AEGM) in ICDs improves arrhythmia diagnosis, reduces risk of inappropriate therapies, and enables monitoring of AF burden. A recently introduced ICD system using a single-lead with floating atrial electrode provides diagnostic capability of a dual-chamber system without placing an additional lead. Data on clinical performance of this system are limited.
Methods: Retrospective analysis of data from 35 consecutive patients implanted with Biotronik VR-T DX devices and Linox Smart DX leads.
Results: Out of 35 patients (77% male, age 52±11.28 years), 32 were followed for a mean of 432 ± 197 days (range 56-765). Of them, 37% had prior VT/VF, 8.5% history of AF, and 66% ischemic cardiomyopathy. DFT testing was performed in 32 patients. Three patients had inadequate DFT defined as safety margin > 10J. During implantation, average pre-amplified and amplified sinus P-wave amplitudes were 2.61±1.39 mV (range 0.9-6.8) and 8.7±4.51 mV (1.4-18), respectively. Although there was a statistically significant decline in P-wave amplitude during follow up measurements, values remained within clinically useful range (Table). R-wave amplitude measurements were stable (Table). There were 15 stored arrhythmia events (11 supraventricular and 4 ventricular) from 11 patients. All reviewed electrograms showed readily interpretable AEGM. Nine (82%) supraventricular events were correctly classified by the device and the therapy was appropriately avoided.
Conclusions: The single lead ICD system using floating atrial electrode provides reliable long term recording of AEGM which facilitates correct interpretation of arrhythmias and allows avoiding inappropriate ICD therapy in the majority of supraventricular events.